In a wireless local area network (WLAN), a mobile device (e.g., PDA or personal digital assistant) accesses the WLAN through a wireless connection to an access point (AP). One commonly used approach for such a WLAN is to base the communications in the network on a time slot or time slicing approach, such as a Time Division Multiple Access (TDMA) approach in which the various devices in the WLAN must be synchronized in order to communicate with each other. In a conventional WLAN, access points (e.g., local area network access points or LAP's) provide access for a mobile device to the WLAN and to other networks, such as hard wired local area networks and global networks, such as the Internet.
The Bluetooth protocol is one example of such a wireless network based on Time Division Multiple Access (TDMA). The Bluetooth technology is described in the Bluetooth specification, available from Bluetooth SIG, Inc. (see also the www.bluetooth.com web site), the entire teachings of which are incorporated herein by reference. This technology provides for a common attachment approach for different devices, and so enables mobile phones, laptops, headsets, and PDA's to be easily networked in the office and eventually in public locations. Other standards, such as the IEEE (Institute of Electrical & Electronics Engineers) 802.11 and ETSI (European Telecommunications Standards Institute) HIPERLAN/2, provide a generally similar wireless connection function as Bluetooth and may be used to support WLAN communications. See the IEEE 802.11 “Wireless LAN Medium Access Control (MAC) and Physical Layer Specifications,” the entire teachings of which are incorporated herein by reference. See also the ETSI specifications for HIPERLAN/2, such as ETSI document number TR 101 683, “Broadband Radio Access Networks (BRAN); HIPERLAN Type 2; System Overview,” the entire teachings of which are incorporated herein by reference
Both the IEEE 802.11 and ETSI HIPERLAN/2 protocols differ from the Bluetooth protocol, in that the IEEE 802.11 and ETSI HIPERLAN/2 protocols use a spread spectrum rather than a frequency hopping approach to sharing a channel between noncoordinated users (e.g., users of the same spectral band that make no effort to avoid cross-interference). To coordinate nodes within a IEEE 802.11 or HIPERLAN/2 network a series of timing beacons are used. These beacons ensure that the timing of the nodes can be synchronized to that of the access point for that network. The HIPERLAN/2 protocol differs from the IEEE 802.11 protocol in that the HIPERLAN/2 protocol uses an Asynchronous Transfer Mode (ATM) approach. Thus the HIPERLAN/2 protocol provides for the breaking of incoming IP packets into a number of smaller packets that are transferred to the destination node in a time division approach (e.g., TDMA) manner which avoids collisions. The approach of the IEEE 802.11 protocol attempts to reserve the wireless medium in order to send the whole packet, and if there is a packet collision, the IEEE 802.11 approach is to back off an amount of time (e.g., of random duration) before retrying.
The Bluetooth protocol provides for a single Bluetooth piconet consisting of one master device and up to seven slave devices that are synchronized to a common clock so that the devices can exchange data. The Bluetooth protocol assumes that different piconets are not synchronized.